The present invention relates to methods of molding fasteners, e.g., the hook component of a hook and loop fastener, and methods of making molds to perform such molding.
Molded hook and loop fasteners include an array of fastener elements integrally molded with and extending from a base. The fastener elements are formed in small mold cavities in a molding device. The mold cavities typically include undercuts for molding loop-engaging shapes such as hooks or mushroom heads.
Often the mold cavities in which the elements are formed have no moving parts, the fastener elements being pulled from the mold cavities by resiliently distorting the molded fastener elements. A running strip of fastener elements is generally molded on a rotating mold roll, e.g., as described in U.S. Pat. No. 4,794,028, the disclosure of which is incorporated by reference herein. For discrete items, cyclable injection molding techniques are employed. In either case, the mold comprises a stack of thin plates which, when in correct registration, define a plurality of mold cavities. Each of the thin plates includes a portion of the mold cavity, taken along an axial cross-section through the cavity, so that when the plates are properly aligned these portions align to define a complete mold cavity.